<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>css-notes</title>
  <style>
    div {
      text-align: center;
      border: 2px solid #a1a1a1;
      padding: 10px 40px;
      background: #dddddd;
      width: 350px;
      border-radius: 25px;
      -moz-border-radius: 25px; /* 老的 Firefox */
    }
  </style>
</head>
<body>
<div>border-radius 属性允许您向元素添加圆角。</div>
</body>
</html>
